Woven-wire resistance and method of forming the same



Sept. '10, 1946. E. M. PATTERSON I 27,407,326

WOVEN-WiRE RESISTANCE AND METHOD OF FORMING THE SAME Filed Jan. 30,.1943 FIG.

IN l/EN-TOR E. M PATTERSON flack/Km A T TORNE k Patented Sept. 10, 1946WOVEN-WIRE RESISTANCE AND METHOD OF FORMING THE SAME Everett M.Patterson, Waterbury, 001111., assignor to Bell Telephone Laboratories,Incorporated, New York, N. Y., a corporation of New York ApplicationJanuary 30, 1943, Serial No. 474,130

4 Claims.

This invention relates to electrical resistance devices and a method offorming them, and more particularly to resistance devices in which theresistance values obtained at various points along the resistance mustbe in accordance with a required pattern.

An object of the invention is to provide an inexpensive resistance ofso-called tapered form and in which no tapered form support for the wireis necessary in the structure.

Another object is to provide a method of readily making a taperedresistance device in which the variation in resistance value taken alongthe length of the device may be in the form of a very steep curve.

A feature of the invention resides in the structure of the resistanceelement.

Another feature resides in a modification providing a reenforcementalong an edge of the resistance element.

In the drawing:

Fig. 1 shows one form of resistance element embodying the invention;

Fig. 2 is an enlarged view of a portion of the resistance shown in Fig.1;

Fig. 3 is an enlarged cross-sectional view of a portion of Fig. 2 takenon the line 3-3;

Fig. 4 is an enlarged view corresponding to Fig. 2 but showing amodification of the invention;

Fig. 5 is an enlarged cross-sectional view of a portion of Fig. 4 takenon the line 55; and

Fig. 6 is a view in perspective of a potentiometer with a resistanceelement constructed in accordance with the invention and mounted on abody of the potentiometer.

In constructing resistance elements for use in potentiometers andrheostats requiring that the resistance value shall change in accordancewith a predetermined curve when a wiper contact is moved over and inengagement with turns of a resistance wire supported in the structure,the resistance wire is often wound on a card-type support of taperedform, the wire-wound cardtype support being later bent into the form ofa ring and mounted on a cylindrical body of the device so that a wipercontact may be rotated over and in contact with turns of the wirelocated on an edge of the card-type support. In some cases very preciseand sudden changes in resistance values are required and the card-typesupport must be very accurately formed and have an edge portionembodying relatively steep curves. When the curves required on thecardtype support are of very steep form, it is found difficult toaccurately wind wire on the steep curved portions of the card-typesupport and to prevent the turns of wire from slipping along the curvedportions of the support. Notches or other means must be provided on atleast the curved edge portion of the card-type support to form rests forthe turns of wire extending about the edge of the card-type support. Thenotches or other means for the purpose must be accurately made and insome cases very closely spaced. The manufacture of the card-type supportis therefore quite expensive.

In the present invention no card-type support for the resistance wire isrequired. The invention is a woven wire type resistance, the wire beingwoven into a warp in a required pattern.

As shown in Fig. 1 the resistance element 1 comprises a warp 8 usuallymade of insulating material and a woof 9 of resistance wire. The warp 8comprises a plurality of spaced threads and the woof 9 is a suitablelength of resistance wire Woven back and forth across the warp in apredetermined pattern, the picks of wire being run entirely across thewarp at some points and only part way across the Warp at other points.It will be seen that by varying the length of the picks of resistancewire in accordance with a predetermined pattern a resistance element maybe made having a change in value from point to point in accordance witha required resistance changing curve.

Assuming that the woven resistance of the pattern shown in Fig. l isused as the resistance element in a resistance device having a, wipercontact and the wiper contact is operated entirely along the resistanceelement to successively engage the picks of resistance wire to changethe resistance value in a circuit the resistance value will be changedin accordance with the pattern of the resistance Wire. When the Wipercontact is traveling from'point It to point II the increase inresistancewill be theoretically in equal steps the value of each ofwhich will be the value of two picks of the resistance wire. From pointit to point t2 the increase in resistance will be more gradual sincesome picks of resistance wire are shorter than preceding picks. Frompoint I2 to point I? the increase in resistance for each step will bemuch greater since each pick of resistance wire is longer than apreceding pick. From point I i-to point !5 the increase in resistancewill be quite gradual since each pick of resistance wire is shorter thana preceding pick. From point 5 to point 16 the increase in. resistancewill be in equal steps. since all picks of 3 the resistance wire betweenthese points are of equal length. The ends of the resistance wire in thewoof ii are identified as I! and [8.

The manner in which the resistance element is made is indicated in theenlarged views in Figs. 2 and 3 in which the warp 8 contains the threadsI9 to 55, inclusive. The resistance wire Eli to form the woof 9 is woveninto the warp 8 and so that the picks extend alternately over and underthe warp threads in a common and well-known manner in weaving indicatedin Fig, 3. To obtain a required change in resistance value from point topoint in the woven resistance, however, the picks of resistance wire arerun at some points entirely across the warp 8 and at other points arerun only part way across the warp, the length of each pick beingdetermined by the resistance pattern required. It will be seen as shownin Fig. 2 that the picks 5'! and 53 extend entirely across the warp 8and that the next two picks 59 and 60 are shorter than the picks 5? and58 and the wire 56 returns through the warp 8 without passing around thewarp thread IS. The picks BI and 62 are shorter than the picks 59 and 60since the wire 56 does not pass around the warp threads l9 and 2B butreturns across the warp 8 at the position of the warp thread 21. Thepicks 63, 64, G5, 66, 61 and 53 ar of equal length and do not extend tothe warp thread 2!. than the: picks 6i and 6?. It will be quite obviousat this point in the description that the resistance may be made to havea predetermined resistance curve characteristic by making the picks ofwire shorter or longer as required and that to point out and indicatethe length of each succeeding pick would only unnecessarily lengthen thespecification. To shorten the specification and at the same timesufficiently describe the invention it seems only necessary to now pointout that by increasing the length of the picks of wire as hown at thepoints 69, 10 and H the resistance curve may be made to have a steeplyrising characteristic. At these points it will be seen that each upwardrun of the wire is longer than the preceding one by an amount equal tothe spacing of two warp threads.

In Figs. 4 and 5 a modification of the invention is shown. In this casethe warp 12 of the resistance 13 contains a reenforcing means along oneedge of the warp 12. The reenforcing means serves in some measure tostiffen the structure and provides a backing for the loops of wirelocated on one edge of the resistance. The reenforcing means may be, forinstance, a wire 14 having a coating 15 of insulating material, theinsulated wire 14 being located along the lower edge of the warp 12 sothat the loop portions 16 of the resistance wir 11 are supported by theinsulated wire 14. The resistance 13 shown in Fig. t may be constructedin the same manner as the resistance 1 shown in Figs. 1, 2 and 3, exceptfor the inclusion in the structure shown in Fig. 4 of the reenforcementmeans involving the insulated wire '14, the warp 12 having the samenumber of threads as the warp 8 but having the insulated wire 14 runningparallel with and next to the warp thread 55 and through the loopportions 76 of the resistance wire.

The resistance 1 or 13 may be used as a resistance element in aresistance device 18 shown in Fig. 6. The resistance element isidentified in this figure as '19 and is wrapped around a flanged Theyare, therefore, shorter cylindrical body 89 in which a. wiper contact 8|is rotatably supported to rotate over and engage an edge of theresistance element la. The ends of the warp may be tied together or besecured to the body in any suitable manner to hold the resistanceelement 19 in the form of a ring, the original straight edge portion ofthe element being disposed for engagement by the wiper contact 8i. Whenthe resistance element 19 is constructed like the resistance 1 shown inFigs. 1, 2 and 3 the pressure of the wiper contact 8| against the edgeportion of the resistance element should be very light to prevent thepressure of the wi er contact from distorting the engaged edge of theresistance element. When the resistance element 19 is constructed likethe resistance l3 and includes a reenforcing means such as the insulatedwire 14 the reenforcing means serve as a backing for the loop portions16 of wire on the engaged edge of the resistance element and preventsdistortion of the loop portions 16 of wire on the edge portion of theresistance enga ed by the wiper contact 8|.

What is claimed is:

1. A woven-wire type resistance comprising a Warp of spaced threads anda woof of picks of resistance wire woven transversely through said warpand in which between certain predetermined points taken along saidresistance picks of resistance wire are made in predetermined varyinglengths, extending from one edge of said warp and partially across saidwarp to make the resistance value taken from one of said points toanother follow a predetermined curved resistance changing pattern.

2. A woven-wire resistance comprising a warp of spaced threads, aresistance wire woven back and forth in a plurality of picks ofpredetermined varying lengths across said warp, one end of each of saidpicks being located on one edge of said warp and providing loops of saidwire along an edge of said resistance and a' cord included in said warpand extending through the loops of said wire and providing a backingmeans for the loops of said wire.

3. A woven-wire resistance comprising a warp of spaced threads, aresistance wire woven back and forth across said warp in a series ofpicks of predetermined different lengths and supported by the threads insaid warp, all of said picks ex tending to one edge of said warp, saidwirehaving loop portions formed along an edge of said resistance and aninsulated wire in said warp and extending through the loop portions ofsaid resistance wire and providing a reenforcement for said warp and abacking means for the loop portions of said resistance wire.

4. A method of forming a tapered resistance having one long straightedge and a, required pattern of resistance change measured at variouspoints along the resistance comprising weaving a length of resistancewire back and forth across a warp of spaced threads to form a seriesofpicks of resistance wire, extending all picks to one edge of said Warpand making some picks in different predetermined lengths so that theunit resistance values of the picks will be non-uni form and the changesin resistance values measured at various points along the resistancewill be in accordance With the required resistancechange pattern. I

EVERETT M. PATTERSON.

